Ultramax is loose in center of corners

J

jacobsdad

Member
Last Friday night my daughter raced for her 3rd night ever. I was not able to be there with her, but she called me with regular updates. She had trouble with the kart running loose in the center of the corners getting 4 wheel drift. It straightened out then was loose in the rear when coming off the corners. I had her drop air pressure in the left side 1 pound and bring the right side to the same pressure as the left side. I told her this for lack of anything else to have her do. She is fairly mechanical but without being there didn't want her to attempt any involved changes. She reported back that in the feature race she was better coming off the turns but in the center of the turn she was loose. The track was very muddy so that didn't help much.
I have been working and out of town since then, so tonight was the first I was able to look at her kart. Now, what can I do to tighten it up before Friday nights racing? She is a beginner so I am working on getting her confidence up before I have her worry about speed, so if we lock her down too tight and loose a little speed it will be fine. She needs seat time and some confidence before she runs too much faster.
She is in an older Ultramax possibly a pro force. I am not sure what it is for certain. She is in an open clone class, clone motor no restrictor 350 pound minimum weight. The numbers now are
front 42%
rear 58%
left 58%
cross 46%.
Total weight 365 pounds. Tires are Maxxis pinks and blues front stagger is 1 1/8 inch stagger rear is 3/4. The right rear wheel is almost touching the frame and the left rear is 3/4 inch out from the frame.
I am pretty sure the frame is bent or has something wrong with it, I am having trouble getting the weights where I want them. It is a borrowed kart, it will be going home after Friday. I am looking for something I can do to improve her cornering without spending a lot of time on the scales. The problem I have is I just got home this evening after being gone for several days. Homework comes first, so she was only in the shop with me for about a half of an hour. Tomorrow night when we go to the shop we will be limited on time, by the time she gets home from school and I leave for work. It is not an ideal situation this week to get things done to the karts.
I did not write down what the toe adjustment is on the kart, and it is old enough it doesn't have camber adjustments. I don't want to go bending on the spindles to adjust camber because as stated before it is a borrowed kart. I just want to tighten it up to get her some seat time and some confidence. If she still loves racing as much as she has this season I will consider buying her a kart of her own for next season, this season is just a test run to see if she really likes racing.
 
Just looking at your numbers, I'm going to say kart is probably pushing on entry, then the front end grips and makes it loose. for quick fix, I would move weight forward. seat would be best thing. if not possible, then move lead or add lead, even if over minimum, to get above 46% nose. Getting the front to turn first is most important.

i know driver says loose center out, but is easiest thing for driver to remember last thing that happened. If you have video, watch front tires on entry closely. I would bet it does not want to turn in even.

Print off the nogoats sheets to keep with you at the track.

Randy Major used to have some great articles about helping the driver communicate what is happening.

Keep encouraging her. KJarting is a great way for dads and daughters to bond. My 21 year old still enjoys hanging with dad at the track.


ps. When she gets fast, she'll be intimidating enough that you don't have to be!!!

Good luck
 
Looking at numbers you need about 46% front weight and up cross to about 58%. Try 5psi on rt side and 4psi on left side for air pressure
 
Get ur left side weight down to around 56% also. If she still is in a 4 wheel drift add right side weight but I think she tight on exit with that set up.
 
Cross 60
Left 56
Nose 45.5

If you have pills for the front end let me know which ones you have so we can set it to the correct settings to at least get a starting point to work with. I see that you only are going to ride it one more time this Friday night. I would also try to get the stagger up on the kart. 1 1/2 front and 1 1/8 rear. Set the right rear at 3/16 off the frame and the left rear 1" off the frame. These numbers should be a good starting point on that kart. Before looking at any set up help sheet ya gotta get in the general set up numbers that the kart needs rather then just scratch your head and wonder why isn't the set up help sheets not helping you..... If you are still loose with this set up you may want to get to work on tires and add bite to them with a biting prep agent. If you need anything at all please feel free to shoot me a message or call.

JR Curtis
309 2810266
 
I don't think I've ever seen a set of number like yours. The LF is very heavy and the LR is very light. The balance, front to rear, is really different. I'm no setup man, but these numbers are way different from any I've seen.

Total 365
Front 42 %
Left 58 %
Cross 46 %

Left Front % 27.01%
Left Front lbs 98.6

Right Front % 15.01%
Right Front lbs 54.8

Left Rear % 31.00%
Left Rear lbs 113.15

Right Rear % 27.01%
Right Rear lbs 98.6

Front Cross lbs 43.80 Difference Right to Left
Front Cross % 80.00%

Rear Cross lbs (14.55) Difference Left To Right
Rear Cross % -14.81%
 
Thanks for all of the advice.
My son has been racing for 2 years now, we have his kart set up right where we want it to be, but this one has been a problem getting set up. I don't think there are any pills in the front end. I have had both sides apart to replace bearings and the king pin bolts and all I can find is the bolt, bearings and washers.
 
Al, that is why I think this kart is bent. Both front spindles are maxed out as far as they will go and 46% is the highest I can get on the cross.
The only weight we have on the kart now is one 10 pound weight on the left side of the seat.
 
I knew someone would post some good numbers to shoot for with that chassis. as far as getting cross, I would first check to see if bumpers or nerfs are binding. Body or seat in a bind would also hold cross out. More front stagger could be used to get more cross but would also affect camber numbers in front end.
I would get the other numbers first by physically moving weight, then see how far off you are.

Good Luck
 
Thanks, I will check all of that. I moved the 10 pound weight from the left side of the seat to the right side of the kart a little forward of center, and will add another 10 pounds to the nose just left of center. When she gets home from practice I will put her on the scale and see what that did. I will also loosen the seat and see if it is binding. It does have rubber spacers between the seat and all of the mounting points. The nerf bars are mounted with rubber spacers and they wiggle when I shake them.
Right now I have the nose off of the body. She brushed the wall and broke part of the nose, so I did some fiberglass repair. Waiting for the resin to set up good before putting the nose piece back on. That is one good thing about a fiberglass body, it is easy to patch up small repairs.
 
JPR57 said:
Jacobsdad, listen to what ever JR Curtis tells you about a U-Max. He rides them and wins on them.
Click to expand...

I wrote his numbers and advice in my notebook, those are what I am going to shoot for. Only other thing I am going to do in addition is move the left front wheel in a little close to the frame. Compared to my sons Ultramax her left front is out 1/4 inch farther from the frame than his.
Like I said, she is a new driver. This season was just an experiment to see how much she liked racing when she was out in the dirt. She made 2 nights but had engine trouble, then she injured herself and was out until last week. Now my goal is to get the kart to handle for her driving so she can get comfortable with driving. She is still scared when she gets in traffic, and is giving the wheel too much steering. when she gets confident enough to relax things will improve I just want to make it easy to get her there.
One goal was to finish a race, that is done. Next goal was to keep her from getting lapped, that too was accomplished. Next goal is to get her seat time to learn how to drive. After that then she can think about moving from the back of the pack up to the middle or front of the pack.
 
jacobsdad said:
Al, that is why I think this kart is bent. Both front spindles are maxed out as far as they will go and 46% is the highest I can get on the cross.
The only weight we have on the kart now is one 10 pound weight on the left side of the seat.
Click to expand...
If theres no pills its probably before the proforce and very early centerforce, most of those were 1 1/8 tube chassis and could be wore out
 
Moving the left front in will help tighten it up, good move. Also the suggestion to increase the front stagger is a good one. That will help increase cross for you, these old umax's were good around 54% if it is indeed a proforce or centerforce, which if there is no camber adjustment then that will be what it is. I wouldn't go over 1 3/4 front stagger and would probably shoot for 1 5/8 as a target, that should get your cross close and help tighten her up. Hope this helps, good luck!

PS, if there is a pill adjustement it would be pressed into the spindle itself. It should look like and oval washer.
 
XXX#40 said:
If theres no pills its probably before the proforce and very early centerforce, most of those were 1 1/8 tube chassis and could be wore out
Click to expand...

Ultramax went to 1 1/4" in the middle of 1998. They made 2, one cheaper that they called an ST model that was Mig weld and the standard model that was Tig weld (and had adjustable nerf bars and all the stars laser cut into the frame :))

In 1999 they made some changes and called it the centerforce.

2000 made more changes to the centerforce and also came out with the proforce with caster adjustment in the front.
 
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